Drawing on data from the National Center for Education Statistics’ Early Childhood Longitudinal Study on the kindergarten class of 1998-99, the study examined attendance records as well as parent and teacher surveys.

Most striking was the contrast between the absenteeism of children from low-income families and their better-off peers, showing children from poor families to be four times more likely to fall into the chronic-absenteeism category, which was defined as being absent more than 18 days.

The study also found that, on average, children who missed 10 percent or more of kindergarten school days scored lower in general academic testing once they reached 1st grade.